JPH06340416A - Preparation of zeolite wherein silica and if necessary, oxide of quadrivalent element is used as base material - Google Patents

Abstract

PURPOSE: To attain good control of crystallization and to increase crystallization rate by preparing an aq. mixture contg. a silicon source in a complex form, optionally, a tetravalent element source in a complex form, a modifier which generates hydroxyl ions by hydrothermal decomposition and a structuring agent which instructs and stabilizes the formation of the objective zeolite, heating the aq. mixture under specified conditions and firing the resultant precipitate.

CONSTITUTION: An aq. mixture contg. a silicon source in the form of an M_2/nSiF₆ complex (I) [M is a proton, an alkali (alkaline earth) metal ion, a transition metal ion, an NH₄ ion or a quat. NH₄ ion], optionally, a tetravalent element source in the form of an M_2/nT'F₆ complex (II) (M is the same as M in the complex I and T' is Ti, Ge, Zr and/or Sn), a modifier (Mod) and a structuring agent (Str) in an Mad to SiF₂ ^2- molar ratio of 0.25-8.0 and an Str to SiF₆ ^2- molar ration of 0.04-3.0 is prepd., adjusted to pH0-6.5 and heated to ≥120°C to form a precipitate. This precipitate is fired at ≥450°C.

COPYRIGHT: (C)1994,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel process for the preparation of zeolites based on silicon oxide and optionally oxides of tetravalent elements. In particular, the present invention relates to a novel method for producing silica-based MFI zeolite. The invention also relates to a process for the production of MFI zeolites based on silica and oxides of titanium, germanium, zirconium and / or tin.

[0002]

Zeolites are crystallized tectosilicates. This structure is composed of TO ₄ tetrahedra of the assembly to form a three-dimensional skeleton structure by sharing oxygen. In the most common aluminosilicate type zeolites, T represents tetravalent silicon and trivalent aluminum. The molecular-sized cavities and channels present in this framework accept cations that complement the charge deficit resulting from the presence of tetravalent aluminum in the tetrahedra. Instead of aluminum, gallium and optionally tetravalent elements such as boron or beryllium can also be used.

This composition has the general formula x ₁ M ₁ ^{n1 +} : x ₂ M ₂ ^{n2 +} ... [(y ₁ T ₁ : y ₂ T ₂
...) O ₂ (y ₁ + y ₂ + ...)] ^x- z ₁ A ₁ : z
₂ A ₂ ... [where the symbols in square brackets represent the composition of the skeletal structure in the T element, and the other symbols correspond to the species present in the micropores of the skeletal structure, M ₁ , M ₂ ... Is a complementary cation when x is greater than 0, and A ₁ , A ₂
... represents water, an ion pair, or a molecule]. Especially when the T element is the only tetravalent one, the skeleton structure has no negative charge (x = 0) and therefore there are no complementary cations M ₁ , M ₂ ...

Each type of zeolite has its own unique pore structure. The variation in the size and shape of the pores for each type is
This leads to variations in adsorption properties. Only molecules with a particular size and shape can enter the pores of a particular zeolite. Due to these outstanding properties, zeolites
It is particularly suitable for the purification or separation of gas or liquid mixtures, for example the separation of hydrocarbons by selective adsorption.

The chemical composition, as well as the nature of the elements present in the TO ₄ tetrahedron and the nature of the exchangeable complementary cations, are also important factors in the adsorption selectivity of the products, especially in the catalytic properties. . They are used as catalysts or catalyst supports in the decomposition, reforming or modification of hydrocarbons and in the formation of many molecules.

Although there are many natural zeolites that are aluminosilicates, their availability and properties do not always meet the requirements of industrial applications. Therefore, the search for products with novel properties has led to the synthesis of various zeolites, especially of the aluminosilicate type.
Many examples of this type include A zeolite (US Pat. No. 2,882,243), X zeolite (US Pat. No. 2,882,244), Y zeolite (US Pat. No. 3,130,007). , L zeolite (French Patent 1,224,154), T zeolite (French Patent 1,223,775), ZSM5 zeolite (US Pat. No. 3,702,886), ZSM12 zeolite (US Pat. No. 3). , 832,449) and ZSM48.
Zeolites (French Patent No. 15,132) are mentioned.

Zeolites generally crystallize out of aqueous solution. However, their low solubility results in substantial amounts if the reaction medium is only a slightly supersaturated solution containing the T element in the form of a polycondensable species for the formation of the framework structure of the zeolite. Prevent the formation of crystals. As supersaturation of such solutions increases, amorphous gels are formed,
The solid phase contains most of the T element in the form of hydroxides and oxides.

The usual method of synthesizing zeolites consists of converting the gel to zeolite crystals by the hydrothermal method using a dissolution-recrystallization mechanism. The crystal-forming seeds are renewed in solution by polycondensation via continuous dissolution of the solid phase of the gel, which acts as a reservoir for the reactants. This conversion is facilitated by the presence of a transfer agent (OH ⁻ or F ⁻ ) capable of transferring the polycondensable species by solution. The reaction medium also contains a structuring azent, which is incorporated into the micropore space of the skeletal structure during crystallization, thus controlling the composition of the skeletal structure and stabilizing its structure Help to turn into.

Nevertheless, the method of synthesis from gels has some drawbacks, in particular: -heterogeneous composition and organization of the gel, which undergoes dissolution of the gel to form a solution. , Which can lead to variations in the composition and properties of the species produced by,-generally inconsistent dissolution,-aging over time (which reduces its reactivity),-supersaturation of the solution (which Is required by the properties of the gel and can vary depending on the above factors),-a practical technical problem: stirring the gel (which can be very viscous) and allowing the entire reaction medium to Difficulties in obtaining a uniform temperature, inclusion of gel particles into the zeolite crystals during their growth, which leads to crystal inhomogeneities.

The object of the invention is to avoid the above-mentioned drawbacks.
It is to provide a method for producing FI zeolite. More specifically, the object of the present invention is to provide an improved process for the preparation of MFI zeolites which results in better control of the crystallization of the zeolite and faster reaction rates of the zeolite crystallization. This method is based on a completely different principle than previously known methods, since it does not use a reaction medium which initially contains a highly reactive gel.

Another object of the invention is the production of zeolites, especially containing silica, and zeolites based on silica and oxides of tetravalent elements selected from titanium, germanium, zirconium and / or tin. To provide an equally suitable method for the production of

In the following description of the invention, T represents a tetravalent element including Si ⁴⁺ and T ', and ^T'is Ti ⁴⁺ , G
e ⁴⁺ , Zr ⁴⁺ and / or Sn ⁴⁺ .

[0013]

More specifically, the present invention relates to the production of silica-based MFI zeolite by (1) .M _{2 / n} SiF ₆ complex (I) (where M is a proton or an alkali metal). Ion, alkaline earth metal ion,
A silicon source in the form of a valence n cation such as a transition metal ion, an ammonium ion or a quaternary ammonium ion), optionally M _{2 / n} T′F ₆ complex (II), where
M has the meaning given above, and T'represents one or more sources of the tetravalent element T'in the form of titanium, germanium, zirconium and tin), OH by hydrothermal decomposition under reaction conditions ^- causing ion chemistry (Mod), structure determination agents to direct and and stabilizing the production of zeolite (Str), to prepare an aqueous homogeneous mixture containing, (2) the reaction mixture to a temperature of at least 120 ° C. Heating to form a precipitate, which is then separated, and (3) calcining the precipitate at a temperature above 450 ° C. to remove the structure-determining agent encapsulated in the channels. The present invention relates to a method for producing a silica-based MFI zeolite characterized by:

Another embodiment of the process of the present invention is a reaction mixture for controlling the rate of elimination of OH ^- ions generated by the thermal decomposition of chemical agents, described below as "pH adjusters" (Mod). To include an additive (Adj).

[0015]

DETAILED DESCRIPTION OF THE INVENTION The source of the element T (Si ⁴⁺ + T ') is
It exists in a completely soluble form in the new reaction mixture. When these sources are used to cause the nucleation and growth of zeolite crystals, the hydrolysis reaction forms polycondensable species from such sources. This hydrolysis reaction is caused by the controlled increase in the pH of the solution. To this end, soluble chemical agents known as pH adjusters are included in the reaction, whose hydrothermal decomposition provides the required OH ^- anion.

As mentioned above, the soluble source of the T element is
It is preferably a fluorine-containing complex of the M _{2 / n} TF ₆ type (formula V). In formula (V), M is a proton, an alkali metal, preferably sodium, an alkaline earth metal, preferably calcium, a transition metal from Group VIII of the Periodic Table, especially 2
It represents an element having an atomic number of 5 to 30, a cation having a valence of n such as ammonium ion or quaternary ammonium.
In this last case, see the definition of formula (IV) described below.

Some examples of complexes of formula (V) are: -silicofluoric acid or sodium, potassium, calcium,
Fluorosilicate of barium or ammonium, -Titanium fluoride of sodium, potassium, rubidium, cesium, magnesium, calcium, copper, zinc or ammonium, -Germanic acid fluoride of sodium, potassium, rubidium, cesium or ammonium Salts-Sodium, potassium, rubidium, cesium, magnesium, manganese, nickel, copper, zinc, cadmium or ammonium fluoride zirconates, -Sodium, potassium, magnesium, calcium,
Barium, manganese, cobalt, nickel, copper, zinc,
Silver, cadmium or ammonium fluorostannate. From a practical point of view, these complexes can be obtained by dissolving an oxide or hydroxide of element T in hydrofluoric acid. The fluorine-containing complex of formula (V) is stable in acidic or slightly acidic media (pH below about 6).

According to the method of the present invention, the fluorine-containing complex is
pH is the next type of reaction

[Chemical 3] Is hydrolyzed into a hydrolyzed complex when it increases. The hydrolyzed species formed are polycondensable and can be used to crystallize the zeolite.

A feature of the method of the present invention is the generation of OH ⁻ ions in situ to control the rate at which the hydrolyzed species are formed and concentrated. These consume HF, and the above two equations (1) and
Move (2) to the right. For this purpose, a pH adjusting agent (hereinafter referred to by the abbreviation "Mod") is used, which is a reaction of the following type at the temperature at which the zeolite is synthesized:

[Chemical 4] Disassemble by. An example of such a pH adjusting agent is urea, which can

[Chemical 5] Decomposes above 100 ° C. However, many other species can also act like urea. Some examples that may be mentioned are substituted ureas, thioureas and substituted thioureas, cyanamides, substituted cyanamides, hexamethylenetetramine and melamine, which can be used alone or in a mixture. Substituted urea and substituted thiourea have nitrogen elements of 1, 2, and
Urea and thiourea substituted with 3 or 4 saturated or unsaturated and / or aromatic-aliphatic groups. Some examples of radicals to be particularly mentioned are alkyl radicals having 1 to 4 carbon atoms, allyl radicals and / or phenyl radicals.

Some examples of substituted ureas and thioureas suitable for the present invention are methylurea, symmetrical dimethylurea, asymmetrical dimethylurea, trimethylurea, tetramethylurea, ethylurea, N-methyl-N. '-Ethylurea, symmetrical diethylurea, asymmetrical diethylurea, triethylurea, tetraethylurea, n-propylurea, symmetrical di-n-propylurea, tetra-n-propylurea, n-
Butyl urea, symmetrical di-n-amyl urea, allyl urea, symmetrical diallyl urea, asymmetric diallyl urea, phenyl urea,
N-methyl-N'-phenylurea, N-methyl-N-phenylurea, N-ethyl-N'-phenylurea, N-ethyl-N-phenylurea, N, N-dimethyl-N'-phenylurea, Symmetrical diphenylurea, methylthiourea, symmetrical dimethylthiourea, asymmetrical dimethylthiourea, trimethylthiourea, tetramethylthiourea, ethylthiourea, N-methyl-N'-ethylthiourea, N, N-dimethyl-N'-ethylthiourea, symmetrical diethylthiourea urea,
Asymmetric diethyl thiourea, triethyl thiourea, tetraethyl thiourea, n-propyl thiourea, N-methyl-
N'-n-propylthiourea, N-ethyl-N'-n-
Propylthiourea, symmetrical di-n-propylthiourea, asymmetrical di-n-propylthiourea, N-ethyl-N, N '
-Di-n-propylthiourea, n-butylthiourea, i
-Butylthiourea, d-tert-butylthiourea, tert-butylthiourea, allylthiourea, N-methyl-N'-allylthiourea, N, N-dimethyl-N'-allylthiourea, N-ethyl-N'-allylthiourea , N, N-diethyl-N'-allylthiourea, symmetrical diallylthiourea,
Phenylthiourea, symmetrical diphenylthiourea.

Substituted cyanamides are cyanamides in which the nitrogen atom is replaced by one or more aliphatic and / or aromatic groups as defined above. Those which can be particularly mentioned as an example of the substituted cyanamide are methyl cyanamide,
Dimethyl cyanamide, ethyl cyanamide, diethyl cyanamide, di-n-propyl cyanamide, di-n-butyl cyanamide, allyl cyanamide, diallyl cyanamide,
Phenyl cyanamide and diphenyl cyanamide.

Another embodiment of the method of the present invention is "p
Including an additive (Adj) in the reaction mixture to control the rate of OH ^- ion release generated by the thermal decomposition of a chemical agent described as "H-modulator" (Mod).

For the purpose of adapting the rate at which the pH is raised and its final value to the rate at which the polycondensable hydroxylated species are formed and their concentration, the pH modifier is hydrolyzed. OH obtained by varying the speed
^- it may be useful to limit the concentration of anions. At this time, it is beneficial to include an additive (Adj) in the reaction medium. For example, this additive may be formaldehyde, which slows the decomposition of the pH adjusting agent, for example by forming urea formamide oligomers, or the resulting O 2.
It may be a salt such as ammonium chloride which limits the concentration of H ^- anion.

Structure-determining agents suitable for carrying out the present invention are:

[Chemical 6] Wherein R ₁ , R ₂ , R ₃ may be the same or different and represent a straight or branched chain alkyl group having 1 to 6 carbon atoms, preferably a propyl or butyl group. Tertiary amines, -formula (IV)

[Chemical 7] Wherein R ₁ , R ₂ , R ₃ , R ₄ may be the same or different and are straight or branched chain alkyl groups having 1 to 6 carbon atoms, preferably propyl or butyl groups. A compound of formula (III) and formula (IV), wherein the nitrogen atom is replaced by a phosphorus atom.

A preferred feature of the present invention is that the structure-determining agent is a compound capable of providing a tetrapropylammonium or tripropylammonium cation. The structure-determining agent is advantageously included in the reaction mixture in the form of a quaternary ammonium salt of formula (IV) or an amine of formula (III).

The reaction mixture, expressed as a molar ratio, has the following composition: Mod / (Si F ₆ ^2- + T'F ₆ ^2- ) (Mod = pH regulator): 0.25-8.0, preferably 1. 0-4.0, Str / (Si F ₆ ²⁻ + T′F ₆ ²⁻ ) (Str = structure determining agent): 0.04 to 3.0, preferably 0.08 to 1.5, H ₂ O / (Si F ₆ ^2- + T'F ₆ ^2- ): 15 to 300, preferably 25 to 200 Adj / (Si F ₆ ^2- + T'F ₆ ^2- ) (Adj = additive or pH adjusting agent): 0 It preferably has a value of 8.0 to 6.0.

In another embodiment of the process according to the invention, it is possible to produce zeolites based on silica and oxides of tetravalent elements. In this case, the tetravalent element T '(T'
= Ti, Ge, Zr and / or Sn) is T'F
_{^{6 2- / (Si F 6 2-}} + T'F 6 2 -) molar ratio is 0.001 in
The amount is preferably 0.50 to 0.005 to 0.25.

In a practical embodiment of the present invention, the reactants are mixed at ambient temperature, usually 15-25 ° C.
The pH of the reaction medium before heating is 0 to 6.5, preferably 2 to
A value of 5.5 is beneficial. This can be adjusted by adding acids or bases. Preference is given to using an aqueous ammonia solution. When the base used is organic, it must have weak structure-determining properties so that it does not compete with the added structure-determining agent. Thus, some examples of suitable bases for the present invention are methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine and triethylamine.

In order to allow rapid crystallization without the formation of gels in the middle, MFI zeolite is present at a proportion of up to 50% of the equivalent of silica Si O ₂ contained in the M _{2 / n} Si F ₆ source. The crystals can be dispersed in the reaction medium. Any MFI zeolite can be used as crystal nuclei regardless of their chemical composition. Zeosilit
e) Preference is given to using MFI which contains only silicon in the framework structure.

The zeolite is crystallized by heating the reaction medium at a temperature of 120 to 250 ° C., preferably 140 to 200 ° C. for the time required for crystallization according to the usual operating modes known in the art for the synthesis of zeolites.
As one indicator, the heating time may be 2 to 200 hours. Heating and crystallization are preferably carried out in a vessel or autoclave, for example with a coating of polytetrafluoroethane. The reaction mixture may or may not be stirred. After the heating step, the pH of the reaction medium is 6.
Advantageously, it is between 5 and 12.0, preferably between 7.0 and 10.0.

The process for producing zeolites according to the invention by crystallizing the zeolites from a homogeneous medium can be carried out under the conditions of earth gravity or microgravity or under zero gravity.

The favorable effects that can be expected from weightlessness are: -there is no sedimentation during the formation of the crystals, which suggests that the crystals grow constantly because sedimentation hinders growth. , There is no convective flow leading to the formation of new nuclei due to crystal-to-crystal collisions and the "breeding" phenomenon.

Weightlessness is defined as a state in which the influence of gravity is eliminated. When an object is no longer affected by the earth's gravitational force, it is in zero gravity. Weightlessness can be obtained, for example, when compensating for the earth's attractive force by orbiting an object. At this time, centrifugal force compensates the attractive force of the earth (satellite flight).

According to the method of the present invention, the crystallization step can be carried out under normal earth gravity conditions. That is, in this case, the weight g of the weight (which is also a measure of the acceleration of the free fall motion of a heavy object) is about 9.808 m / s ² . It should be understood that g varies depending on the latitude and altitude of the object. The values given as an example are specified at sea level at the latitude of the city of Paris.

According to the present invention, g _i can be smaller than acceleration due to the attractive force of the earth. The lower bound is not exact and may be as close to zero as possible.
From a practical point of view, g _i is 10 ⁻⁶ g to 1 g, preferably 1
It falls within the range of 0 ^-5 g to 1 g. This range is given as an example and the invention is not limited thereto.

After the crystallization step on earth or in space, the crystals are separated on earth by conventional solid-liquid separation methods, in particular by filtration or centrifugation. The crystalline precipitate is beneficially washed to remove impurities, especially cations or anions that are not bound or incorporated into the structure.

The resulting precipitate (designated as "zeolite" precursor) is silica and optionally the following general formula (VI) (Si _96-x T _x ) O _192.4 ± 1 (S ⁺ F ⁻ ) (VI), a crystalline product of a zeolite of the type based on an oxide of the tetravalent element metal T ′ according to (VI). In the formula (VI), -x is 0 to 12.0, preferably 0 to 6.0, and -T is Si ⁴⁺ and the following tetravalent element T ': Ti, Ge, Z.
r and / or Sn, and -S ⁺ represents the cation arising from the structure-determining agent. More specifically, it is a cation originating from an amine of formula (III), a quaternary ammonium type cation of formula (IV),
Or it represents the same compounds in which the nitrogen atom is replaced by a phosphorus atom.

If the zeolite produced consists essentially of silica, the zeolite precursor is of the general formula (V
_{Ia) Si 96 O 192 · 4} ± 1 (S + F -) is a crystalline product of the silica substrate zeolitic according to (VIa). In formula (VIa), -S ⁺ represents a cation generated from the structure-determining agent.

[0039] When the manufactured zeolite is further an oxide of silica and tetravalent element, said zeolite precursor, the following general formula _{(VIb) (Si 96-x} T 'x) O 192 · 4 ± 1 is a zeolite-type crystalline product based on 1 (S ⁺ F ⁻ ) (VIb) based on silica and a tetravalent element T ′. In the formula (VIb), -x is smaller than 12.0, preferably 0.1 to 6.
0, -T 'represents the following tetravalent elements: Ti, Ge, Zr and / or Sn, and -S ⁺ represents the cation arising from the structure-determining agent.

The zeolite precursor of formula (VI) is easy to handle and undergoes a calcination operation leading to the formation of zeolite. It is also possible to carry out the drying at a temperature of 30 to 100 ° C., generally under atmospheric pressure, before the firing operation.

Calcination is then carried out, which removes the precipitate (which may be dried) to decompose organic species such as structure determinants contained in the precipitate.
It consists of heating to a temperature above 0 ° C, preferably above 500 ° C.

MFI zeolites based on silica according to the general formula (VII) (Si _96-x T _x ) O ₁₉₂ (VII) and, optionally, oxides of the tetravalent element T ′ are obtained. To be In formula (VII), -x is 0 to 12.0, preferably 0 to 6.0, and -T is Si ⁴⁺ and the following tetravalent element T ': Ti, Ge, Z.
represents r and / or Sn.

[0043] In the method of the present invention, silica based MFI zeolite, or the following formula in the following formula _{(VIIa) Si 96 O 192 (} VIIa) (VIIb) (Si 96-x T 'x) O 192 (VIIb) MFT based on the silica and the oxide of tetravalent element T '
It is possible to obtain zeolite. In formula (VIIb), -x is less than 12, preferably 0.1 to 6.0, and -T 'represents the following tetravalent elements: Ti, Ge, Zr and / or Sn. . MFI obtainable by the method of the invention
Zeolites can be identified in particular by plotting the diffraction patterns of the precursors that give rise to them.

The zeolite precursor of the present invention has an orthorhombic crystal and an X-ray diffraction pattern as shown in Table 1. In this table, the extreme value d _{hkl of} each surface spacing (equal distance) is given. These are the minimum concentration and the maximum concentration (concentration limit) of the element T'incorporated into the skeletal structure of the zeolite before calcination, more specifically, T '/ (Si +
T ') ratio (T' = Ti ⁴⁺ , Ge, Zr ⁴⁺ and / or S
n ⁴⁺ ).

Diffraction patterns can be obtained with an X-ray diffractometer using the usual powder method with Kα irradiation of copper. The sample-specific interplanar spacing d _hkl is calculated by the Bragg equation from the portion of the diffraction peak represented by the angle 2θ.
measurement error of d _hkl △ (d _hkl) is evaluated as a function of the absolute error △ (2 [Theta]) in measuring the 2 [Theta] by the Bragg equation. An absolute error Δ (2θ) of ± 0.2 ⁰ is currently allowed. The relative intensity I / I ₀ assigned to each value of d _hkl is calculated from the height of the corresponding diffraction peak. To characterize its intensity, the next symbol, FF
= Extremely strong, F = strong, mF = medium to strong, m
= Medium, mf = Medium to Weak, f = Weak are often used. The value of the capacity V ₀ of the crystal mesh of zeolite before calcination is a function of the substitution of silicon by the element T ′.

The obtained main lines are shown in Table 1 below.

[Table 1] Described in.

The zeolites obtained by the process of the present invention are used to catalyze many reactions such as disproportionation or alkylation reactions of petroleum fractions, hydrocracking and hydrogenation or reforming processes. You can Also, the zeolite produced by the method of the present invention is very suitable for use as a catalyst in the reaction of hydroxylating phenols and phenol ethers. Regarding usage conditions, see French Patent Application No. 87/15
See No. 247.

Other objects, features and details of the invention will become more apparent from the following examples, which are provided by way of example only.

[0049]

EXAMPLE 1 A series of tests (1a-1e) were carried out in the preparation of silica-based zeolites by a method using a pH modifier (urea or cyanamide) but no additives.
The reaction mixture formed is shown in Table 2.

[Table 2] Corresponding to the molar composition described in. The amount used in each test corresponds to 1/15 of the composition expressed in mol. In water, - silicon source: sold by PROLABO, Inc. (NH _{4) 2}
Si F ₆ (98% by weight or more),-Structural determinant: tetrapropylammonium bromide Pr ₄ NBr (98% or more) sold by FLUKA, -pH regulator: urea (99.5% in tests 1a-1b). As described above, a solution of the reaction mixture was obtained by dissolving cyanamide (98% or more, MERCK) in Test 1e). The initial pH of the solution was adjusted to the values listed in Table 2 by adding a few drops of 28% ammonia. When used with nucleating agents in some tests, they are finely ground MFI zeolite crystals (ie, Zeocyllite). The amounts listed as% in Table 2 are the amounts of (NH ₄ ) ₂ Si F used.
It is related to the mass of silica SiO ₂ contained in ₆ . In an autoclave coated with polytetrafluoroethane, the reaction mixture was treated at the temperature and time (days) shown in Table 2.
Heated at. The obtained results are shown in Table 2. The solids yield ρ collected was calculated on the basis of the SiO ₂ used and the zeolite crystallization rate is expressed as% by weight. The meanings of the abbreviations in Table 2 are as follows. -Mod: pH adjuster-pHi: initial pH-pHf: final pH-agit: stirring-t ° C: temperature ° C The chemical analysis value of the sample when the impurities are removed by dissolving the sample in boiling water is represented by the formula (VI). ) And the X-ray diffraction spectrum is as shown in Table 1.

Example 2 A series of five tests were carried out showing that it is possible to include an additive (Adj) for the purpose of changing the rate at which the pH is raised in order to obtain purer crystals. Test is 2%
Was carried out by the method of Example 1 using the nucleating agent of. Table 3
Is 1 mol of (NH ₄ ) ₂ Si F ₆ , 0.1 mol of Pr ₄
The number of moles of pH modifier or additive included in the reaction mixture containing NBr and 100 moles of water is given.
The amount used per test corresponds to 1/15 of the composition given below in molar units. The reaction mixture was heated in an autoclave at 170 ° C. for 2 days without stirring. Table 3 shows the obtained results.

[Table 3] Shown in.

Example 3 In this example, a silicon oxide based MFI zeolite is prepared in a homogeneous medium by two methods. That is, one method is to perform the operation in weightlessness (3a) and the other is to perform the operation on the ground (3b). Two similar reaction mixtures 3a and 3 were prepared by the method described below.
Prepared b. Of distilled water 7.2 g, as _{follows, (NH 4) 2 Si F} 6 of -0.712g (99.99 wt%, marketed by ALDRICH Co.), -0.532G of tetrapropylammonium bromide Pr ₄ NBr (sold by FLUKA Co.), and (sold by FLUKA Co.) cyanamide N = C-NH ₂ of -0.504G, was continuously dissolve. The composition of the reaction medium in molar units is 1 mol of (NH ₄ ) ₂ Si F ₆ , 0.
5 moles of Pr ₄ NBr, 3 moles of N = C-NH ₂ and 10
0 mol H ₂ O. Two resulting solutions 3a and 3
b is coated with polytetrafluoroethane, nominal capacity 1
Quantitatively transferred to two 8 ml autoclaves. The fill ratio is thus about 45%. The two autoclaves were left at ambient temperature for 10 days. The autoclave containing solution 3a was then placed on a satellite (microgravity = 10 ⁻⁵ g) in a weightless state at 23 ± 5 ° C. and after one day heated at 170 ° C. for 68 hours (in order to raise the temperature to 170 ° C. It takes 2 hours and 40 minutes). It was then allowed to cool to a temperature of 23 ± 5 ° C. within 28 hours. It was kept at zero weight for 9 days at this final temperature before it was returned to the ground, and opened 2 days after this return. The autoclave containing solution 3b also underwent the same operation as the first autoclave for the same amount of time, but everything was done above ground. After opening the two autoclaves, their contents were filtered and the collected solids were analyzed by various methods (microscopic method, X-ray, chemical analysis). The results are shown in Table 4 below.

[Table 4] Described in. The pH of the solution went from 4 to 9 during the course of the synthesis.

Example 4 A series of tests (4a-) for the preparation of zeolites based on silica and titanium oxide by the method with pH modifiers (urea or cyanamide) but without additives.
4j) was carried out. The prepared reaction mixture is shown in Table 5.

[Table 5] Corresponding to the molar composition described in. The amount used in each test corresponds to 1/15 of the composition expressed in mol. In water: Silicon source: (NH ₄ ) ₂ sold by PROLABO.
Si F ₆ (more than 98% by weight),-Titanium source: 60% aqueous solution of H ₂ Ti F ₆ sold by ALFA-Structural determinant: Tetrapropylammonium bromide Pr ₄ NBr sold by FLUKA (98%). ), PH adjuster: A solution of the reaction mixture was obtained by dissolving urea (99.5% or more, MERCK) in Tests 4a to 4i and cyanamide (98% or more, MERCK) in Test 4j. . The initial pH of the solution was adjusted to the values listed in Table 5 by adding a few drops of 28% ammonia. When used with nucleating agents in some tests, they are finely ground MFI zeolite crystals. The quantities given as% in Table 5 relate to the mass of silica Si O ₂ contained in the (NH ₄ ) ₂ Si F ₆ used. In an autoclave coated with polytetrafluoroethane, the reaction mixture was heated at the temperature and time (days) described in Table 5. The results obtained are shown in Table 5. The yield ρ of the collected solids is calculated for Si O ₂ + Ti O ₂ was used, and the zeolite crystallization rate is expressed as weight%. The meanings of the abbreviations in Table 5 are as follows. -Mod: pH adjuster-pHi: initial pH-pHf: final pH-agit: stirring-t ° C: temperature ° C. Chemical analysis of samples 4c, 4g and 4i when impurities were removed by dissolving the sample in boiling water. Indicate the presence of 0.9, 0.4 and 17% by weight titanium, respectively.

Example 5 A series of showing that it is possible to use a mixture of pH regulators or to include additives (Adj) in order to modify the rate at which the pH is raised in order to obtain purer crystals. Seven tests were conducted. The test was carried out by the method of Example 4 using 2% nucleating agent. Table 6 shows that 1 mol of (N
_{H 4) 2 Si F 6,} 0.25 mol of H ₂ Ti F _6, 0.
The number of moles of pH adjusting agent or additive included in the reaction mixture containing 1 mole of Pr ₄ NBr and 100 moles of water is given. The amount used per test corresponds to 1/15 of the composition given below in molar units. The reaction mixture was heated in an autoclave at 170 ° C. for 2 days without stirring. Table 6 shows the obtained results.

[Table 6] Shown in.

[0054] Two in Example 6 Example 6 test is the method of the present invention corresponds to a method for producing a MFI zeolite containing in addition to germanium element of silicon element. In this case, it is preferable to start with a reactant which does not contain an alkali metal or alkaline earth metal cation in order to minimize the formation of the corresponding insoluble germanate. The molar composition of the reaction mixture is listed in Table 7. The amount used in each test corresponds to 1/15 of the composition expressed in mol. HF4 in slight excess
H ₂ by dissolving Ge O ₂ in 0% aqueous solution
A solution of Ge F ₆ was prepared. This solution is H ₂ Ge F ₆
It contained about 10 moles of water per mole. Table 7
31% aqueous solution of H ₂ Si F ₆ (Prolabo
In company Ltd., it was added to contain H ₂ Si F ₆ 1 mole to about 18.5 moles of water). 0.25 mol of tetrapropylammonium and 1.5 mol of H ₂ Si F ₆ introduced per mol.
Molar urea was dissolved in the mixture. Then the pH of the mixture was adjusted by adding a 40% aqueous solution of methylamine.
From 4 to 5. The solution contained about 2.5 moles of water per mole of methylamine. Add water 50
The reaction mixture was finally brought to completion by giving a H ₂ O / (Si + Ge) molar ratio of. 1% Nucleating agent was added as in Example 4. The reaction mixture was heated at 170 ° C. for 1 day. The results obtained are shown in Table 7.

[Table 7] Shown in. The yield ρ of the collected solids was calculated based on the SiO ₂ + used.
It is calculated on the basis of the sum of the TiO ₂ and the zeolite crystallization rate is expressed as% by weight. The crystals were washed with hot water to remove ammonium germanate type impurities, and then the germanium content in the crystals was measured. This is 2.5% and 1 for samples 6a and 6b, respectively.
It was found to be 0%.

[0055] Two test in Example 7 Example 7 by the method of the present invention, MFI containing in addition to tin or zirconium element of silicon element
It corresponds to a method for producing zeolite. Two reaction mixtures 7a and 7b (corresponding to the molar composition in test 4g) were prepared by replacing H ₂ Ti F ₆ by Na ₂ Sn F ₆ and Na ₂ Zr F ₆ (STREM) respectively according to the method described in Example 4. Prepared. The reaction mixture was heated at 170 ° C. for 1 day. After crystallization under the conditions described in test 4, two solids were obtained by filtration and washed with hot water. X-
Line crystal analysis showed two MFI zeolites containing 3.1% tin (Sample 7a) and 1.3% zirconium (Sample 7b).

Example 8 In this example, an MFI zeolite based on silicon oxide and titanium is prepared in a homogeneous medium by two methods.
That is, one method is to perform the operation in weightlessness (8a) and the other method is as a comparison on the ground (8b), respectively. Two similar reaction mixtures 8a and 8b were prepared by the method described below. Of distilled water 7.2 g, as _{follows, (NH 4) 2 Si F} 6 of -0.712g (99.99 wt%, marketed by ALDRICH Co.), -0.532G of tetrapropylammonium bromide Pr ₄ NBr (sold by FLUKA, Inc.), and urea O = C (NH ₂₎ of -0.48g ₂ (99.5% or more,
(Sold by MERCK), was continuously dissolved. To this solution was added 0.309 g of a 53% aqueous solution of H ₂ Ti F ₆ (sold by ALPHA). The pH was adjusted to 4 by adding 0.04 g of 28% ammonia solution. Finally, 0.0024 g acting as a nucleating agent on this mixture
MFT crystal (zeocillylite) was added. The molar composition of the reaction medium is 1 mol of (NH ₄ ) ₂ Si F ₆ ,
0.25 mol of H ₂ Ti F ₆ , 0.5 mol of Pr ₄ NBr
, 2 moles of O = C- (NH _{2) 2} and 100 moles of H ₂
It is O. The two resulting solutions 8a and 8b were quantitatively transferred to two autoclaves coated with polytetrafluoroethane and having a nominal volume of 18 ml. The fill ratio is thus about 45%. The two autoclaves were left at ambient temperature for 10 days. Next, the autoclave containing the solution 8a was placed on a satellite (microgravity = 1
0 ^-5 g) at 23 ± 5 ° C in a weightless state, and one day later, heated at 170 ° C for 68 hours (temperature was 170 ° C).
It takes 2 hours and 40 minutes to raise the temperature.
Finally, it was allowed to cool to a temperature of 23 ± 5 ° C. within 28 hours. It was kept at zero weight for 9 days at this final temperature before it was returned to the ground, and opened 2 days after this return. The autoclave containing solution 8b also underwent the same operation as the first autoclave for the same amount of time, but everything was done above ground. After opening the two autoclaves,
Their contents were filtered and the recovered solids were analyzed by various methods (microscopic method, X-ray, chemical analysis). The results are shown in Table 8 below.

[Table 8] Described in. The pH of the solution is 4 to 8.5 during the synthesis process.
Became.

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[Procedure amendment]

[Submission date] October 16, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

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[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 6

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[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 7

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[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 9

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[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

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As mentioned above, the soluble source of the T element is
It is preferably a fluorine-containing complex of the M _{2 / n} TF ₆ type (formula V). In formula (V), M is a proton, an alkali metal, preferably sodium, an alkaline earth metal, preferably calcium, a transition metal from Group VIII of the Periodic Table, in particular an element with an atomic number of 25-30, an ammonium ion or Represents a cation with a valence of n, such as quaternary ammonium. In formula (V), n is preferably 1 or 2.
It In this last case, see the definition of formula (IV) described below.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

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According to the method of the present invention, the fluorine-containing complex is
The next type of reaction when the pH increases

[Chemical 3] It is hydrolyzed to the pressurized water decomposition complex depending on. Reaction formula (1)
The octahedral complex obtained according to m has a m of about 3 or less to 1 or more.
Is a number and is obtained according to reaction formula (2).
The body m is between about 2 and about 4. The hydrolyzed species formed are polycondensable and can be used to crystallize the zeolite.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Frederik Hofne, Saint-Marin, France, Ryu de Tantourier, 4 (72) Inventor Jean-Michel Popa, Drancy, France, Rue Roger Breton, 2

Claims (22)

[Claims] 1. In the production of a silica-based MFI zeolite, (1) .M _{2 / n} SiF ₆ complex (I) (where M is a proton, an alkali metal ion, an alkaline earth metal ion,
A silicon source in the form of transition metal ions, ammonium ions or cations of valence n such as quaternary ammonium ions), a chemical agent (Mod) that produces OH ⁻ ions by hydrothermal decomposition under reaction conditions, a zeolite A structure determinant (Str) that directs and stabilizes the formation of the following molar ratios: Mod / (SiF ₆ ²⁻ ) = 0.25-8.0, Str / (SiF ₆ ²⁻ ) = 0 0.04 to 3.0, wherein the initial pH of the reaction mixture is 0 to 6.5, and (2) the reaction mixture is heated to a temperature of at least 120 ° C to form a precipitate. Silica, which is then separated and (3) calcining the precipitate at a temperature above 450 ° C. to remove the structure-determining agent encapsulated in the channels. Base material of MFI zeolite Granulation method. 2. A reaction mixture wherein one or more sources of the tetravalent element T'is M _{2 / n} T'F ⁶ complex (II) (wherein M has the meaning given above and T'is A method according to claim 1, characterized in that it is added in the form of titanium, germanium, zirconium and / or tin. 3. T'F ₆ / (SiF ₆ ^2- + T'F ₆ ^2- )
Has a molar ratio of 0.001 to 0.50, preferably 0.005
3. The method of claim 2 wherein ˜0.25. 4. The method of claim 1, wherein a pH adjusting agent is included in the reaction mixture. 5. The molar ratio of Adj / SiF ₆ ²⁻ is 0 to 8.
Method according to claim 4, characterized in that it is 0, preferably 0-6.0. _6. The molar ratio of Mod / SiF ₆ ²⁻ is 1.0 to
The method according to claim 1, wherein the method is 4.0. 7. The Str / SiF ₆ ²⁻ molar ratio is 0.08.
7. The method according to any one of claims 1 to 6, characterized in that 8. The process according to claim 1, wherein the molar ratio of H ₂ O / SiF ₆ ^{2− in} the reaction mixture is 15 to 300, preferably 25 to 200. 9. The method according to claim 1, wherein the pH of the reaction mixture is 2.0 to 5.5. 10. The pH of ammonia, methylamine,
10. The method according to claim 9, characterized in that it is adjusted by adding a base selected from the group consisting of dimethylamine, trimethylamine, ethylamine, diethylamine and triethylamine. 11. The method according to claim 1, wherein the silicon source is fluorosilicic acid or an alkali metal, alkaline earth metal or ammonium fluorosilicate. 12. The source of the tetravalent element is alkali metal, alkaline earth metal or ammonium fluorotitanate, fluorogermanate, fluorozirconate and / or fluorostannate. The method according to any one of claims 1 to 11, characterized in that. 13. A complex of formula (I) and formula (II) is obtained by dissolving oxides or hydroxides of the elements Si and T ′ in hydrofluoric acid. 11. The method according to 11 or 12. 14. The pH adjusting agent is urea, substituted urea, thiourea, substituted thiourea, cyanamide, substituted cyanamide, hexamethylenediamine, or melamine, according to any one of claims 1 to 13. Method. 15. The method according to claim 14, wherein the pH adjusting agent is urea. 16. The method according to claim 1, wherein the additive or the pH adjusting agent is formaldehyde or a salt. 17. The structure-determining agent is represented by the formula (III): Wherein R ₁ , R ₂ , R ₃ may be the same or different and represent a straight or branched chain alkyl group having 1 to 6 carbon atoms, preferably a propyl or butyl group. Tertiary amine, formula (IV): Wherein R ₁ , R ₂ , R ₃ , R ₄ may be the same or different and are straight or branched chain alkyl groups having 1 to 6 carbon atoms, preferably propyl or butyl groups. A compound of formulas (III) and (IV) in which the nitrogen atom is replaced by a phosphorus atom, the compound being selected from the group consisting of: The method described in. 18. The method according to claim 1, wherein MFI zeolite crystals are added as crystal nuclei. 19. The zeolite comprises a reaction mixture of 120-120.
Crystallized by heating to a temperature of 250 ° C, preferably 140-200 ° C.
8. The method according to any one of 8. 20. The method according to claim 1, wherein the zeolite is crystallized under the conditions of earth gravity or microgravity, or in a weightless state. 21. Gravity is from 10 ⁻⁶ g to 1 g, preferably 10
21. The process according to claim 20, characterized in that the zeolite is crystallized under conditions such that it lies in the range from ^-6 g to 1 g. 22. The final pH of the reaction medium is 6.5-12.
Method according to any of claims 1 to 20, characterized in that it is 0, preferably 7.0 to 10.0.